Interlink between lightning activity of hailstorms and their radar characteristics

Abstract

The time course and the relationship of radar and lightning characteristics of the powerful hail clouds of the North Caucasus are considered. The studies were conducted in 2016-2018 at the automated meteorological radar complex ASU-MRL, which provided simultaneous acquisition and processing of radar data from the MRL-5 and 4-point network of LS-8000 lightning detection sensors, visualization of thunderstorm discharges on the background of the radar reflectivity map, as well as measurement complex of radar and thunderstorm cloud characteristics, including their maximum radar reflectivity Zmax, heights, volumes and water content of clouds at different reflectivity values, frequency of intracloud lightning discharges (VHF), “cloud-to-ground” discharges with positive (LF+) and negative polarity (LF-), current and duration of discharges. An analysis of the results showed that lightning discharges begin in the developing hail clouds of the North Caucasus when their maximum radar reflectivity reaches Zmax ≥ 40 dBZ, the frequency of discharges increases with increasing reflectivity, integral water content and enhancing the process of precipitation formation. The highest thunderstorm activity is noted at Zmax≈ 70-75 dBZ. Most low-frequency discharges of LF- and LF+ types are observed on the windward flank in the zone of intensive precipitation formation, and the majority of high-frequency VHF discharges are on their leeward side. Seeding of hail clouds with glaciogenic reagents with anti-hail rockets also leads to an increase in the frequency of discharges of all types.